WO Publication No. 84/04352 purportedly describes a tubular joint or connector of box and pin members having two-step tapered threads. Two metal to metal seals of complementary engaging sealing surfaces are provided. Reverse angle torque shoulders at the end of the pin member and the interior termination of the box member and hooked threads further characterize the joint and box and pin members.
U.S. Pat. No. 4,623,173 purportedly describes a screw joint coupling for oil pipes. A main sealing portion is provided with a sealing portion which is axially convex at an end of a male screw, and with a sealing portion which is tapered at an inner side of a female screw, and an end point of the male screw butting an end part of a stopper formed at the inner side of the female screw.
U.S. Pat. No. 4,624,488 purportedly describes a tubular connection that has cooperating internal frusto-conical sealing surfaces on a counterbore of the box member and a free end of the pin member. The internal sealing surface of the pin member inclines inwardly substantially at fourteen degrees from the axis of the tubular connection adjacent the end of the pin member. The angle of the incline of the box internal sealing surface is substantially the same as that of the pin internal surface. A pilot surface or bull nose disposed from a distal-proximate end to the distal end of the pin member inclining to a lesser extent than the angle of the incline of the internal surface of the pin member being substantially parallel to the axis of the connection; defines an increased end-of-pin flat thickness.
U.S. Pat. No. 7,334,821 purportedly describes a threaded tubular connection with a male threaded element and a female threaded element. The male threaded element has male threading and a free end, with a non-threaded lip between the threading and the free end. The female threaded element has an internal tapered female threading and a non-threaded portion between the female threading and a lug. The female threaded element comprises an annular axial abutment surface. After complete makeup of the male threading in the female threading, the free end bears against the annular axial abutment surface, which other bearing surfaces radially interfere and are under metal-metal contact pressure to constitute metal-metal sealing surfaces.
In the '821 patent, another axial abutment surface thus is formed on a front surface of the free end of the male threaded element, and a single lip sealing surface is disposed on the lip at an axial distance from the end of the threading. The lip comprises, between the distal axial abutment surface and the single lip sealing surface, an appendix having a peripheral surface facing the female threaded member that is distinct from the lip sealing surface.
U.S. Publication No. 2014/0145433 purportedly describes a tubular connection including a pin and box member. The pin member has a first thread structure and a helical torque shoulder spaced axially along the pin member from the first thread structure. The box member has a second thread structure and a second helical torque shoulder spaced axially along the box member from the second thread structure. Upon rotation, the helical torque shoulders engage one another.